EP 0170158 A2 19860205 - Fourier plane recursive optical filter.
Title (en)
Fourier plane recursive optical filter.
Title (de)
Rekursiver optischer Filter in der Fourier-Ebene.
Title (fr)
Filtre optique récursif dans le plan de Fourier.
Publication
Application
Priority
US 63593684 A 19840730
Abstract (en)
An optical filtering system (50) in which a signal beam (54) of optical radiation is passed through the optical filtering means a multiplicity of times. The filtering system has an optical Fourier transformer means (14), a spatial filter (18), optical inverse Fourier transform means (20) and a pair of reflectors (38, 40) in the Fourier plane of the spatial filter. An input signal beam to be filtered is optically Fourier transformed by the transform means (14) and is passed through the spatial filter (18) where unwanted frequencies of the signal beam are attenuated. The filtered beam is reflected by one of the reflectors back through the filter and the second mirror reflects it back through the filter a third time. Subsequent reflections back through the filter with a consequent further filtering of the signal beam can be accomplished by appropriately positioning the reflectors. After multiple filtering passes, the filtered beam is extracted for utilization. By maintaining the recursions of the beam in the Fourier plane of the filter, which preferably is of a programmable type, the optical throw of the filter system can be significantly reduced and a flexible imaging system without the restraints of external recursion is realizable in a robust structure with fewer components. An embodiment of the system being used in a heterodyning RF optical filtering system is described.
IPC 1-7
IPC 8 full level
H04B 10/27 (2013.01); G02B 27/46 (2006.01); H04B 10/00 (2013.01); H04B 10/29 (2013.01)
CPC (source: EP US)
G02B 27/46 (2013.01 - EP US)
Designated contracting state (EPC)
DE FR GB IT NL
DOCDB simple family (publication)
EP 0170158 A2 19860205; EP 0170158 A3 19870513; EP 0170158 B1 19900509; AU 4470285 A 19860206; AU 568941 B2 19880114; CA 1254421 A 19890523; DE 3577605 D1 19900613; GR 851762 B 19851126; IL 75154 A0 19850929; IL 75154 A 19900209; JP H0792559 B2 19951009; JP S6141116 A 19860227; NO 167608 B 19910812; NO 167608 C 19911120; NO 852242 L 19860131; US 4645300 A 19870224
DOCDB simple family (application)
EP 85108911 A 19850716; AU 4470285 A 19850709; CA 480456 A 19850430; DE 3577605 T 19850716; GR 850101762 A 19850716; IL 7515485 A 19850509; JP 11059385 A 19850524; NO 852242 A 19850603; US 63593684 A 19840730